The present invention relates to sensing the misfeeding of sheet-like articles, and in particular relates to a caliper for use in a collator for sensing the feeding of multiple signatures to a collating conveyor.
A caliper is used in signature collators. The caliper includes a sensing roll which is positioned adjacent to a signature feeding drum. The drum has grippers which feed signatures past the sensing roll. The sensing roll is positioned relative to the drum so as to move in response to a multiple thickness of material (two or more signatures) conveyed by the drum, but which will not move if a single thickness of material (one signature) is conveyed by the drum. If a double thickness of material is fed, the collated assembly of signatures becomes defective and typically will be rejected in response to the sensing by the caliper.
Depending upon the thickness of the signature being conveyed, the position of the sensing roll must be adjusted. The mechanism for adjusting the position of the sensing roll for known calipers is complicated and cumbersome to operate. This results in substantial time being required for adjustment of the caliper. Also, the known calipers cannot be adjusted for extremely thin products because the many parts of the caliper system which need to be adjusted make fine adjustment impossible.
The present invention is directed to a caliper apparatus constructed so that the time for making the caliper adjustment is on the order of a few seconds as opposed to minutes as required by the prior calipers, and also the thickness of the material which can be handled by the caliper is substantially thinner than the thinnest material which can be handled by previous calipers.
The caliper of the present invention includes a roll which has a perimeter partially defining a gap in the path of movement of the signatures. The roll is supported for rotation relative to a support, and the roll is also supported by the support for movement away from the path of the movement of the signatures. A suitable means senses the movement of the roll away from the path of movement of the signatures.
The support for the roll is mounted for adjustment to a position in which the gap defined by the perimeter of the sensing roll has a thickness greater than the thickness of the signatures being conveyed through the gap and less than the thickness of two signatures. The adjustment of the support, and thus of the roll, is effected in response to positioning a signature between the support and a caliper member mounted adjacent to the support. An adjustable member is provided which holds the support in the position to which it is moved in response to positioning of the signature between the support and the caliper member. Thus, by merely positioning a signature between the caliper member and the support the sensing roll becomes located in the desired position to sense double feeding of signatures. This adjustment can be made in a matter of seconds.
The support for the sensing roll comprises a linkage which includes a pair of arms which extend annularly relative to each other. The sensing roll is supported on one end of one arm for rotation relative to the arm and also for pivotal movement relative to the arm. The sensing roll pivots relative to the arm in response to a double signature being conveyed through the gap partially defined by the sensing roll. The pivoting movement of the sensing roll effects actuation of a suitable sensor.
The aforementioned caliper member is adjacent to the other arm of the linkage. When a signature is positioned between the caliper member and the other arm of the linkage, the linkage pivots and the sensing roll becomes located in a position such that the gap through which the signatures move is of a thickness greater than that of one signature but less than that of two signatures. This occurs automatically because of the relative distances from the point at which the linkage pivots to the sensing roll and to the caliper member.